1. Field of the Invention:
This invention relates to a center locking device of the ball train type for both locking and burglarproof purposes to be provided inside a cap nut for a disc wheel of motor vehicle.
2. Prior Art:
In the conventional disc wheel for a motor vehicle, a flange with a threaded tube is fastened to a hub of an axle, a center hole of a disc is fitted on the threaded tube, a cap nut is screwed on the screwed tube and thus the disc is fastened to the axle. As the disc is generally made of aluminum and has no clamp nut at a boss, it makes good appearance. However, since it has no center locking means, when a driver applies the brakes sharply, the cap nut is liable to become loose. Also, as it has no locking device for the cap nut, the cap nut can be removed easily and accordingly disc wheel are apt to be stolen.